Cleaning vessel walls by moving water jets: Simple models and supporting experiments

Impinging liquid jets are widely used in cleaning-in-place operations to remove product residues and soil layers from vessel walls. The model for adhesive removal of soiling layers by coherent impinging water jets presented by Wilson et al. (2014, Chem. Eng. Sci., Vol. 109, 183-196) is revisited and is applied to a series of cases related to tank and vessel cleaning, including the case of a strong (hard to remove) soil; the case where the jet strikes the wall at an oblique angle; and where the point of jet impact moves across the surface. A subset of the results shows good agreement with new and previously published experimental data. A new analysis is presented for calculating the shape of the region cleared of soil by the point of jet impact moving around, or up and down a surface, which allows the resources (time, liquid, and energy) required to clean a cylindrical vessel to be estimated. Selected jet paths and nozzle motion patterns are compared in a case study which illustrates the potential for designing a cleaning programme. The models make several simplifications and theoretical developments required to generate more accurate results are identified. (C) 2016 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.